There exist methods in the prior art for creating visual databases of geographic locations. However, such databases are of limited use due to the method of acquiring the imagery as well as the kind of imagery acquired. One particular method involves the taking of individual photographs of the location and electronically pasting the photographs on a polygonal mesh that provide the framework for a three-dimensional (3D) rendering of the location. This method, however, is time consuming and inefficient for creating large, comprehensive databases covering a substantial geographic area such as an entire city, state, or country.
Another method uses video technology to acquire the images. The use of video technology, especially digital video technology, allows the acquisition of the image data at a higher rate, reducing the cost involved in creating the image databases. For example, the prior art teaches the use of a vehicle equipped with a video camera and a Global Positioning System (GPS) to collect image and position data by driving through the location. The video images are later correlated to the GPS data for indexing the imagery. Nevertheless, such a system is still limited in its usefulness due to the lack of additional information on the imagery being depicted.
The nature of the acquired imagery also limits the usefulness of such a system. A single image acquired by the video camera contains a narrow field of view of a locale (e.g. a picture of a single store-front) due to the limited viewing angle of the video camera. This narrow field of view provides little context for the object/scene being viewed. Thus, a user of such an image database may find it difficult to orient himself or herself in the image, get familiar with the locale, and navigate through the database itself.
One way to increase the field of view is to use a shorter focal length for the video camera, but this introduces distortions in the acquired image. Another method is to increase the distance between the camera and the buildings being filmed. However, this may not be possible due to the limit on the width of the road and constructions on the opposite side of the street.
The prior art further teaches the dense sampling of images of an object/scene to provide different views of the object/scene. The sampling is generally done in two dimensions either within a plane, or on the surface of an imaginary sphere surrounding the object/scene. Such a sampling, however, is computationally intensive and hence cumbersome and inefficient in terms of time and cost.
Accordingly, there is a need for a system and method for creating a visual database of a comprehensive geographic area in a more time and cost efficient manner. Such a system should not require the reconstruction of 3D scene geometry nor the dense sampling of the locale in multiple dimensions. Furthermore, the images in the database should provide a wider field of view of a locale to provide context to the objects being depicted. The database should further correlate the images with additional information related to the geographic location and objects in the location to further enhance the viewing experience.